期刊
ASTROPHYSICAL JOURNAL
卷 627, 期 2, 页码 L145-L148出版社
IOP PUBLISHING LTD
DOI: 10.1086/432465
关键词
binaries : spectroscopic; nuclear reactions, nucleosynthesis, abundances; stars : abundances; stars : AGB and post-AGB; stars : individual ( CS 29497-030); stars : Population II
Employing spectra obtained with the new Keck I HIRES near-UV-sensitive detector, we have performed a comprehensive chemical composition analysis of the binary blue metal-poor star CS 29497-030. Abundances for 29 elements and upper limits for an additional seven have been derived, concentrating on elements largely produced by means of neutron-capture nucleosynthesis. Included in our analysis are the two elements that define the termination point of the slow neutron-capture process, lead and bismuth. We determine an extremely high value of [Pb/Fe] = +3.65 +/- 0.07 (sigma = 0.13) from three features, supporting the single-feature result obtained in previous studies. We detect Bi for the first time in a metal-poor star. Our derived Bi/Pb ratio is in accord with those predicted from the most recent FRANEC calculations of the slow neutron-capture process in low-mass asymptotic giant branch (AGB) stars. We find that the neutron-capture elemental abundances of CS 29497-030 are best explained by an AGB model that also includes very significant amounts of pre-enrichment of rapid neutron-capture process material in the protostellar cloud out of which the CS 29497-030 binary system formed. Mass transfer is consistent with the observed [Nb/Zr] similar to 0. Thus, CS 29497-030 is both an r+s and extrinsic AGB star. Furthermore, we find that the mass of the AGB model can be further constrained by the abundance of the light odd-element Na.
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